src: port openBSC over libosmo-abis

This is a big patch that ports openBSC over libosmo-abis.
Sorry, the changes that are included here are all dependent
of libosmo-abis, splitting them into smaller pieces would
leave the repository in some intermediate state, which is
not desired.

The main changes are:

- The directory libabis/ has been removed as it now lives in
  libosmo-abis.

- new configuration file format for nanoBTS and HSL femto, we
  need to define the virtual e1_line and attach it to the OML
  link.

- all the existing BTS drivers (nanoBTS, hsl femto, Nokia site,
  BS11 and rbs2000) now use the new libosmo-abis framework.

- use r232 input driver available in libosmo-abis for bs11_config.

- use ipa_msg_recv instead of old ipaccess_read_msg function.

- delete definition of gsm_e1_subslot and input_signal_data.
  These structures now lives in libosmo-abis.

Most of this patch are deletions of libabis/ which has been
moved to libosmo-abis.

This patch also modifies openBSC to use all the new definitions
available in libosmocore and libosmo-abis. In order to do that,
we have replaced the following:

- DINP, DMI, DMIB and DMUX by their respective DL* correspondences.
- SS_GLOBAL by SS_L_GLOBAL
- SS_INPUT by SS_L_INPUT
- S_GLOBAL_SHUTDOWN by S_L_GLOBAL_SHUTDOWN
- SS_INPUT by SS_L_INPUT
- S_INP_* by S_L_INP_* sub-signals
- E1INP_NODE by L_E1INP_NODE vty node

This patch has been tested with:
- one nanoBTS
- the HSL femto with the examples available under libosmo-abis
- BS11 with both dahdi and misdn drivers.
diff --git a/openbsc/src/osmo-bsc_nat/bsc_nat_utils.c b/openbsc/src/osmo-bsc_nat/bsc_nat_utils.c
index 8658c3d..84b23d1 100644
--- a/openbsc/src/osmo-bsc_nat/bsc_nat_utils.c
+++ b/openbsc/src/osmo-bsc_nat/bsc_nat_utils.c
@@ -318,13 +318,13 @@
 	struct msgb *msg;
 
 	if (length > 4096 - 128) {
-		LOGP(DINP, LOGL_ERROR, "Can not send message of that size.\n");
+		LOGP(DLINP, LOGL_ERROR, "Can not send message of that size.\n");
 		return -1;
 	}
 
 	msg = msgb_alloc_headroom(4096, 128, "to-bsc");
 	if (!msg) {
-		LOGP(DINP, LOGL_ERROR, "Failed to allocate memory for BSC msg.\n");
+		LOGP(DLINP, LOGL_ERROR, "Failed to allocate memory for BSC msg.\n");
 		return -1;
 	}
 
@@ -350,7 +350,7 @@
 int bsc_write_msg(struct osmo_wqueue *queue, struct msgb *msg)
 {
 	if (osmo_wqueue_enqueue(queue, msg) != 0) {
-		LOGP(DINP, LOGL_ERROR, "Failed to enqueue the write.\n");
+		LOGP(DLINP, LOGL_ERROR, "Failed to enqueue the write.\n");
 		msgb_free(msg);
 		return -1;
 	}